Yet Mr. Sanders chose to withhold his endorsement of Mrs. Clinton, several Sanders advisers said, because he wants her to take steps to win his confidence before the Democratic convention, where his supporters expect him to speak and Clinton advisers hope he will give her his full-throated backing.

Aides to Mrs. Clinton said she had never expected his endorsement Tuesday night. A statement from the Clinton campaign after the meeting described it as “a positive discussion about their primary campaign, about unifying the party and about the dangerous threat that Donald Trump poses to our nation.” They discussed issues like raising wages and reducing college costs, and “agreed to continue working on their shared agenda, including through the platform development process for the upcoming Democratic National Convention.”

Watch Roland Martin and his expert panel of guests discuss the current state of the 2016 presidential race in the video clip below.

The Sanders campaign released a nearly identical statement, though it emphasized that the two candidates also spoke about “how best to bring more people into the political process” — a reflection of the strong support for Mr. Sanders among young people and independents.

Reuters reports that Sanders has scheduled a national video address to supporters on Thursday night, telling them in an email message that “the political revolution continues.”